This invention is preferably used in conjunction with the prior art filter apparatus described in U.S. Pat. No. 4,735,716 to Petrucci et al, which is assigned to the same assignee as this application. Other relevant prior art patents include U.S. patent numbers:
3,178,022, to Balogh; PA1 3,780,867, to Zirlis; PA1 3,799,347, to McDuffie; PA1 3,883,428, to Waring; PA1 4,029,580, to Lange; PA1 4,104,044, to Lange; PA1 4,125,469, to Henton, et al.; PA1 4,177,145, to Schumacher; PA1 4,192,751, to Henton, et al.; PA1 4,318,809, to Bethel; and, PA1 4,320,000, to Lange, et al.
The prior art filter apparatus, which is described in U.S. Pat. No. 4,735,716, to Petrucci, et al., includes a head, a cartridge, securing means for attaching the cartridge to the head, a filter assembly disposed in the cartridge, an inlet port in the head, and an outlet port in the cartridge, for one-direction flow through the filter assembly. Such a filter apparatus is used in a triple-head structure designed to hold three disposable canisters, e.g. a sediment cartridge, a reverse osmosis (RO) module or cartridge and an activated carbon cartridge. Thus water passing through the apparatus will first be subjected to prefiltering in the sediment filter cartridge. The filtrate then flows to the RO module and is subjected to reverse osmosis filtration to remove dissolved substances and undissolved matter, including bacteria. The permeate from the RO module cartridge will then flow to the activated carbon filter cartridge where dissolved chloride will be removed. The filtrate therefrom is then discharged into a storage tank and is then subsequently used, e.g. for drinking.
A common problem associated with such a system is that upon storage in the storage tank for any appreciable period of time there is a tendency of the tank to impart an unacceptable taste and odor to the water. Typically this is resolved by the installation of an additional final-stage carbon filter between the storage tank and the service faucet. The invention described and claimed herein eliminates the need for a separate final filter in such a system.
U.S. Pat. No. 3,178,022 to Balogh describes a first, forward flow, filter apparatus, and a second, return flow, filter apparatus, each apparatus including a container, and a filter assembly, which is disposed in the container and which has a check valve.
U.S. Pat. No. 3,780,867 to Zirlis describes a one direction, water filter apparatus, which includes a head, a cartridge, securing means, a filter assembly, an inlet port, and an outlet port, wherein the filter assembly includes concentric cylindrical screens with an earth layer therebetween and with charcoal within the inner screen.
U.S. Pat. No. 3,799,347 to MaDuffie describes a bidirectional, oil filter apparatus, which includes a container, two end heads with respective ports, two check valves adjacent to the respective heads, a cylindrical paper filter disposed between the two check valves, for flow in a forward direction, or alternately for flow in a reverse direction.
Prior art U.S. Pat. No. 3,883,428 to Waring describes a one direction, water filter apparatus, which includes a head, a container, a cloth and carbon filter assembly disposed in the container, an inlet port in the head, and an outlet port in the head.
U.S. Pat. Nos. 4,029,580 and 4,104,044 to Lange describe a bidirectional, heat pump filter apparatus, which includes a container, two end heads, two check valves, two filters, two driers, for flow in a forward direction or alternately for flow in a reverse direction.
U.S. Pat. Nos. 4,125,469 and 4,192,751 to Henton, et al describe a bidirectional, heat pump filter apparatus, which includes a container, two end heads, two check valves, a cylindrical fiberglass filter, and two flat end filter pads, for flow in a forward direction or alternately for flow in a reverse direction.
U.S. Pat. No. 4,177,145 to Schumacher describes a bidirectional, heat pump filter apparatus, which includes a container, two end heads, two check valves, alumina filter material, two flat end filter pads, for flow in a forward direction or alternately for flow in a reverse direction.
U.S. Pat. No. 4,318,809 to Bethel describes a bidirectional, heat pump filter apparatus, which includes a container, two end heads, two check valves, a cylindrical fiberglass filter, and two flat end filter pads, for flow in a forward direction, or alternately for flow in a reverse direction.
U.S. Pat. No. 4,320,000 to Lange, et al describes a bidirectional, heat pump filter apparatus, which includes a container, two end heads, four check valves, a cylindrical filter unit having a perforated tube, for flow in a forward direction or alternately for flow in a reverse direction.